The present invention concerns seating units having a reclineable back, and more particularly concerns seating units having a reclineable back with flexible lumbar region.
A synchrotilt chair is described in U.S. Pat. No. 5,050,931 (to Knoblock) having a base assembly with a control, a reclineable back pivoted to the control, and a seat operably mounted to the back and control for synchronous motion as the back is reclined. This prior art chair incorporates a semi-rigid flexible shell that, in combination with the chair support structure, provides a highly-controlled postural support during the body movements associated with tasks/work (e.g., when the back is in an upright position) and during the body movements associated with recline/relaxation (e.g., when the chair is in a reclined position). This prior art chair moves a seated user's upper body away from the user's work surface as the user reclines, thus providing the user with more area to stretch. In fact, moving around in a chair and not staying in a single static position is important to good back health in workers whose jobs require a lot of sitting. However, users often want to remain close to their work surface and want to continue to work at the work surface, even while reclining and relaxing their body and while having continued good postural support. Further, workers often want to selectively choose the amount of maximum recline. In other words, workers often want to lean backward (i.e. recline) a small amount in an intermediate recline position, and yet simultaneously stay an appropriate distance from their work surface. Also, workers prefer not to “fight” with the chair to stay in the intermediate partial-recline positions. Workers also desire an improvement in back support that is comfortable and sympathetic to back movements of the seated user and that allows significant flexing of the user's back, yet that provides uniform and effectively comfortable support, particularly in the lumbar area of the back. It is noted that increased flexibility in a back can tend to result in inadequate support to a seated user. However, too little flexibility in a back support or a non-uniformly-distributed supporting force from a back support (i.e. a back support that is “too stiff”) will be less uncomfortable than desired. Further, the seated user may “fight” with the chair to get comfortable as the seated user tries to stay in various desired lumbar-flexed positions.
Modern customers and chair purchasers also demand a wide variety of chair options and features, and a number of options and features are often designed into chair seats. It is important that such options and features be incorporated into the chair construction in a way that minimizes the number of parts and maximizes the use of common parts among different options, maximizes efficiencies of manufacturing and assembling, maximizes ease of adjustment and the logicalness of adjustment control positioning, and yet that results in a visually pleasing design.
Accordingly, a chair construction solving the aforementioned problems is desired.